三月27号是什么星座

Water falls from the heavens, runs into streams, flows into groundwater, feeds lakes, then evaporates.

Fresh water is abundant despite accounting for less than 3% of the planet’s total supply. But water is very poorly distributed. Our rivers and streams represent a vast web that nourishes the planet’s territories, yet too much of the land is forgotten. Today, more than 660 million people do not have safe drinking water and 2.4 billion live without access to proper sanitation.

Water falls from the heavens, runs into streams, flows into groundwater, feeds lakes, then evaporates. It fuels biodiversity, sustains our crops and animals, helps generate energy and supports our towns and villages. Its scarcity affects people’s daily lives, even if we tend to forget this all too often in the developed world, as water treatment and distribution investment have brought us water on demand – though not always drinkable – through taps in our homes.

We now effectively use water to feed ourselves, as most water (around 69%) is used by agriculture. The irrigation of 20% of farming land makes it possible to produce 40% of our food. Household water use represents just 12% of total consumption.

For a kilogram of roasted coffee, 26 400 litres of water are needed to grow the bushes producing the coffee grains in Africa, South America or Asia, and then to transport and roast them.

What can we do about the remaining 88%? This unseen water used by agriculture and industry is known as “virtual” water. It is needed to produce the goods we consume: from the provisioning of raw materials and processing, through to packaging and distribution and potentially to recycling. Each of these stages in a product’s lifecycle requires water. A cup of coffee provides perhaps the best example. For a kilogram of roasted coffee, 26 400 litres of water are needed to grow the bushes producing the coffee grains in Africa, South America or Asia, and then to transport and roast them. This means that the few dozen millilitres of dark liquid in our cup of coffee leave a virtual footprint of 150 litres of water! This same exercise can be done for a pair of jeans or a steak. Beef wins the virtual water consumption prize, with 15 000 litres per kilogram of meat. A plastic water bottle uses the same amount of water to produce as it can hold (1.5 litres).

John Anthony Allan of King’s College coined the term “virtual” in the early 1990s to refer to the water used in production, but this water could not be more real. International trade circulates 2.32 trillion cubic metres of virtual water a year, or 74 million litres exported or imported every second.

Consequently, just as you can calculate the carbon footprint of an individual, company or country, there is an indicator for the water use of these categories – the water footprint – expressed in cubic metres per person, per day or per year. Globally, the average individual has a water footprint of 1 400 cubic metres per year, or 3 800 litres per day. The disparities are huge. For example, a North American uses 7 800 litres a day, mainly due to high beef consumption of 43 kilograms a year per person.

We destroy around 15 to 18 million hectares of forest (an area approximately the size of Belgium) every year, with 2 400 trees cut down each minute.

Urbanisation and intensive agriculture, soil sealing and deforestation are forcing a change in soil use, and therefore an increase in run-off and depletion of groundwater. We destroy around 15 to 18 million hectares of forest (an area approximately the size of Belgium) every year, with 2 400 trees cut down each minute. The use of synthetic fertilisers and poorly managed irrigation has a destructive impact on ecosystems and biodiversity. For the last 20 years, we have been losing 2 000 hectares a day to soil salinisation, affecting more than 62 million hectares, or 20% of irrigated land. Water artificially contaminated with excess nitrogen causes eutrophication and hypoxia in oceans and rivers. More than 500 dead zones covering 250 000 square kilometres have already been identified – and this figure has been doubling every ten years since the 1960s.

As far as public health is concerned, diarrhoea originating from contaminated water is estimated to cause 842 000 deaths a year.

I could go on. I have witnessed these phenomena first-hand during my photographic expeditions. I have seen the drying-up of the Aral Sea, the floods caused by Hurricane Katrina, and green algae in Brittany.

A change to our development model is therefore long overdue.

The wisdom of long-term thinking is required if water can regain its main role: as a resource for the future, a source of life.

At the country level, catchment agencies have the core purpose of managing resources to guarantee water provision and quality in their areas. To ensure the proper management of water quality, there is a need to work closely with agriculture in the catchment areas. To this end, some farmers have committed to stop using synthetic fertilisers on their lands, making the switch to organic cultivation. This is a positive example of the interconnected nature of environmental issues, because as outlined above, ecosystems are interdependent.

Large-scale water adduction and treatment projects mobilise colossal energy and financing, coordinated by international development and financing organisations or global companies. They are necessary but not enough, as they are mostly connected to urban areas with high populations. In desert countries located next to large bodies of salt water, the use of desalination to make fresh water requires a lot of energy and expense, making this technique difficult to apply to other regions. However, technological progress has made it possible to expect a significant fall in energy needs and, therefore, the associated costs.

At the other end of the spectrum, I would like to pay particular tribute to the non-governmental organisations that work to provide low-cost drinking water where it is needed in rural areas, and to make this supply sustainable by creating local micro-enterprises, a successful form of the social and solidarity economy.

The large-scale works and multitude of local initiatives share the same goal, with different and usually complementary approaches. Often, certain industry players engage in parallel small-scale actions in communities via foundations or local civil society partners. Technology and financing are vital for both water and the climate, but will not be enough to resolve the monumental challenge facing us. The problem is above all related to individual and collective behaviours, conventional wisdom that has to be challenged, together with a development model that is far from sustainable.

We have had all the observation, analysis and dissemination tools for many years, and cannot feign ignorance. In 1972, the Meadows report for the Club of Rome, titled “The Limits to Growth”, warned that we were doomed if current growth and consumption trends continued. After the 1992 Earth Summit in Rio, a Nobel laureate in Physics, Henry Kendall, launched an appeal signed by 1 700 scientists to mobilise policy-makers. Now there are 15 000 scientists of all specialisations from 184 countries who are, once again, warning us that we are heading towards the accelerated destruction of the natural world. For myself, I can point out my own 2012 documentary, A Thirsty World, which remains entirely relevant.